Dynamics of circadian thalamocortical flow of information during a peripheral neuropathic pain condition

• Type: Article in International Scientific Journal
• Date: 2011

Authors

Cardoso Cruz, H (Author) Other; Sameshima, K (Author) Other; Lima, D (Author) FMUP; Galhardo, V (Author) FMUP

Journal

Title: Frontiers in Integrative Neuroscience

Vol. 5

ISSN: 1662-5145

Publisher: Frontiers Media

Indexing

ISI Web of Knowledge

Scopus - 19 Citations

Other information

Authenticus ID: P-008-18H

DOI: 10.3389/fnint.2011.00043

Abstract (EN): It is known that the thalamocortical loop plays a crucial role in the encoding of sensory-discriminative features of painful stimuli. However, only a few studies have addressed the changes in thalamocortical dynamics that may occur after the onset of chronic pain. Our goal was to evaluate how the induction of chronic neuro pathic pain affected the flow of information within the thalamocortical loop throughout the brain states of the sleep-wake cycle. To address this issue we recorded local field potentials (LFPs) both before and after the establishment of neuro pathic pain in awake freely moving adult rats chronically implanted with arrays of multi electrodes in the lateral thalamus and primary somatosen-sory cortex. Our results show that the neuropathic injury induced changes in the number of wake and slow-wave-sleep (SWS) state episodes, and especially in the total number of transitions between brain states. Moreover, partial directed coherence -analysis revealed that the amount of information flow between cortex and thalamus in neuropathic animals decreased significantly, indicating that the overall thalamic activity had less weight over the cortical activity. However, thalamocortical LFPs displayed higher phase-locking during awake and SWS episodes after the nerve lesion, suggesting faster transmission of relevant information along the thalamocortical loop. The observed changes are in agreement with the hypothesis of thalamic dysfunction after the onset of chronic pain, and may result from diminished inhibitory effect of the primary somatosensory cortex over the lateral thalamus. © 2011 Cardoso-Cruz, Sameshima, Lima and Galhardo.

Language: English

Type (Professor's evaluation): Scientific